Biomedical subjects

Q Wu

Publications and source records attributed to Q Wu.

At least 145 records · Page 8Linked to original sources

PubMed2000

The impact of fluctuations in intensity patterns on the number of monitor units and the quality and accuracy of intensity modulated radiotherapy.

The purpose of this work is to examine the potential impact of the frequency and amplitude of fluctuations ("complexity") in intensity distributions on intensity-modulated radiotherapy (IMRT) dose distributions. The intensity-modulated beams are efficiently delivered using a multileaf collimator (MLC). Radiation may be delivered through a continuous (dynamic mode) or discrete (step-and-shoot) sequence of windows formed by the leaves. Algorithms and software that convert optimized intensity distributions into leaf trajectories apply approximate empirical corrections to account for the various effects associated with MLC characteristics, such as the rounded leaf tips, tongue-and-groove leaf design, leaf transmission, leaf scatter, and collimator scatter upstream from the MLC. Typically, the difference between inter- and intraleaf transmissions is ignored. In this paper, using a schematic example of IMRT for head and neck carcinomas, we demonstrate that complex anatomy and severe optimization constraints produce complex intensity patterns. Using idealized intensity patterns we also demonstrate that, for complex intensity patterns, the average window width tends to be smaller and, for the same dose received by the tumor, the number of MUs is larger. We found that as the complexity increases, so does the contribution of radiation transmitted through and scattered from the leaves ("indirect radiation") to the total delivered dose. As a consequence, the lowest deliverable intensity in complex intensity patterns may be significantly greater than that required to provide adequate protection for some normal tissues. Furthermore, since corrections for leaf transmission and scatter effects are approximate and the difference between inter- and intraleaf transmission is ignored, the accuracy of the delivered dose may be affected. Using the results of a simple experiment and a typical intensity-modulated beam for a head and neck case as examples, we show the effect of window width and complexity on the accuracy and deliverability of intensity patterns. Some possible strategies for improving the accuracy and for relaxing the lower limit on deliverable intensity are discussed.

Biophysical Phenomena↗

PubMed2000

Establishment of a polychlorinated biphenyl-dechlorinating microbial consortium, specific for doubly flanked chlorines, in a defined, sediment-free medium.

Estuarine sediment from Charleston Harbor, South Carolina, was used as inoculum for the development of an anaerobic enrichment culture that specifically dechlorinates doubly flanked chlorines (i.e., chlorines bound to carbon that are flanked on both sides by other chlorine-carbon bonds) of polychlorinated biphenyls (PCBs). Dechlorination was restricted to the para chlorine in cultures enriched with 10 mM fumarate, 50 ppm (173 microM) 2,3,4, 5-tetrachlorobiphenyl, and no sediment. Initially the rate of dechlorination decreased upon the removal of sediment from the medium. However, the dechlorinating activity was sustainable, and following sequential transfer in a defined, sediment-free estuarine medium, the activity increased to levels near that observed with sediment. The culture was nonmethanogenic, and molybdate, ampicillin, chloramphenicol, neomycin, and streptomycin inhibited dechlorination activity; bromoethanesulfonate and vancomycin did not. Addition of 17 PCB congeners indicated that the culture specifically removes double flanked chlorines, preferably in the para position, and does not attack ortho chlorines. This is the first microbial consortium shown to para or meta dechlorinate a PCB congener in a defined sediment-free medium. It is the second PCB-dechlorinating enrichment culture to be sustained in the absence of sediment, but its dechlorinating capabilities are entirely different from those of the other sediment-free PCB-dechlorinating culture, an ortho-dechlorinating consortium, and do not match any previously published Aroclor-dechlorinating patterns.

Aroclors↗

PubMed2000

Effects of the Fusarium spp. mycotoxins fusaric acid and deoxynivalenol on the growth of Ruminococcus albus and Methanobrevibacter ruminantium.

The Fusarium spp. mycotoxins fusaric acid and deoxynivalenol (DON) were tested for antimicrobial activity against Ruminococcus albus and Methanobrevibacter ruminantium. The growth of both organisms was inhibited by fusaric acid as low as 15 micrograms/mL (84 microM) but not by DON, at levels as high as 100 micrograms/mL (338 microM). No synergistic inhibitory effect was observed with DON plus fusaric acid. Neither organism was able to adapt to the fusaric acid and responses of each organism to the compound were different. The optical density (OD) maximum for R. albus, but not for M. ruminantium, was diminished after 28 days incubation at concentrations of fusaric acid below 240 micrograms/mL. Inhibition of R. albus started before significant growth had occurred, while M. ruminantium doubled twice before the onset of inhibition. Responses to picolinic acid, an analog of fusaric acid, were also dramatically different between the two microorganisms with M. ruminantium exhibiting a severe lag followed by a complete recovery of growth, while R. albus was only slightly inhibited with no lag. These results suggest that the mechanism of fusaric acid inhibition is specific to each microorganism. This is the first demonstration of the common mycotoxin fusaric acid inhibiting the growth of rumen bacteria.

Animals↗

PubMed2000

[Relationship between interleukin-2, interleukin-2 receptor and the non-and hypo-responsiveness to hepatitis B vaccine].

OBJECTIVE: To study the relationship between interleukin-2 (IL-2), soluble interleukin-2 receptor (sIL-2R) and the non-and-hypo-responsiveness to hepatitis B vaccine. METHODS: Peripheral blood mononuclear cells (PBMC) isolated from 21 non-and -hypo-responders, 22 hyperresponders and 21 chronic HBsAg carriers were incubated in the presence of HBsAg and phytohaemagglutinin (PHA). The levels of IL-2 and sIL-2R in the supernatants of activated cells were measured by an enzyme-linked immunosorbent assay. RESULTS: The average level of IL-2 in the non-and-hypo-responders was significantly lower than that in the hyperresponders (t=8.80, P<0.001), but was comparable to that in chronic HBsAg carriers (q=0.06, P>0.5). Between the hyperresponders and the non-and-hypo-responders, the average sIL-2R levels showed no noticeable difference. CONCLUSION: The results suggest that low level of IL-2 may be one of the causes and mechanisms of non-and-hypo-responsiveness to hepatitis B vaccine.

Carrier State↗

PubMed2000

[Recent advance in studies of new intraaortic axial flow pump: "dynamic aortic valve"].

We have previously proposed and demonstrated the feasibility of a new concept of intraaortic axial flow blood pump, termed "Dynamic Aortic Valve(DAV)". Implanted in the position of aortic valve, DAV can serve as either an assistant pump or a mechanical valve subjected to the power input. It has several merits over the traditional axial blood pumps: (1) better anatomic compatibility and biologic compatibility; (2) little foreign material is to be introduced into the corporeality; (3) better resistance to infection; (4) puncturing power line could be eliminated; (5) promoting the failing heart to recovery; (6) simpler structure and better durability. In our recent studies, the structure of DAV is further simplified and performance improved greatly. The structure of DAV is merely an impeller fixed to a magnetic rotor while held by a central shaft hanging from a rigid supporting cage. The rotor-impeller can be driven by an alternative magnetic field derived from a remote magnet, implying that the magnetic source can even be arranged extracorporeally. The DAV can be driven by a rotational magnet placed at a distance of 60 mm. At the state of maximal output of hydraulic power, the flow rate (FR) generated by DAV reaches 5 L/min against an afterload of 70 mmHg(1 mmHg = 0.133 KPa). The maximal pressure differential (PD) maintained by DAV is 131 mmHg. The results further revealed the feasibility of the concept of DAV.

Aortic Valve↗

PubMed2000

[An experimental study of human tracheal epithelial transfer of human neutrophil defensin gene].

This study was amied at the possibility of production of the human neutrophil defensin in human tracheal epithelial cells when transfected with it's gene by using liposome. The plasmid vector carrying the human neutrophil defensin HNP1 (human Neutrophil Peptide-1) gene was used to transfect the human tracheal epithelial cells cultured in serum-free complement medium by lipofection reagent. Antiserum of HNP1 was prepared and used for the immunocytochemistry staining to detect expression of HNP1 gene in human tracheal epithelial cells. The result showed that recombinant eukaryote expression plasmid-pBabe-Neo-HNP1 could be transducted into human tracheal epithelial cells by liposomal transfection method. Transducted cells showed strong positive staining for HNP by immunohistochemistry assay. It was suggested that HNP1 gene could be productively transduced into human tracheal epithelial cells and expressed by using liposome. Antibiotic peptide gene might be used for gene therapy of respiratory infections.

Cells, Cultured↗

PubMed2000

[Utilization of municipal sludge in agriculture and sustainable development].

Based on the ideas of sustainable development, this paper analyzed the features and disposal situations of municipal sludge and its influence on agricultural and urban development. It is suggested that the land application of municipal sludge is significant and urgent for urban and agricultural sustainable development. Land application of sludge will also be basic outlet for sludge disposal in the future. The key of land application of sludge lies in controlling the content of toxic pollutants in sludge and utilizing sludge scientifically.

Agriculture↗

PubMed2000

Effect of all-trans retinoic acid on growth of xenograft tumor and its metastasis in nude mice.

OBJECTIVE: To study the effect of all-trans retinoic acid on growth of xenograft tumor and its metastasis in nude mice. METHODS: Human gastric cancer BGC-823 and MKN-45 cells were inoculated into spleen subcapsule of nude mice, respectively. The nude mice were subsequently administered with all-trans retinoic acid every other day. Food consuming and body weight of nude mice were measured weekly. Six weeks later, the nude mice were killed. Xenograft tumors in spleen and metastatic tumors in liver were pathologically examined. Microvessel density in the tumors was detected immunohistochemically, and serum carcinoembryonic antigen was measured by radioimmunoassay. RESULTS: After the nude mice were fed with all-trans retinoic acid, the growth of splenic tumor and its liver metastasis were inhibited and the metastatic rates decreased by 50% (BGC-823) and 33.3% (MKN-45), respectively. The microvessel density in splenic and hepatic tumors reduced by 28.58% and 35.47% (BGC-823), 19.45% and 14.52% (MKN-45), respectively. The concentration of carcinoembryonic antigen decreased by 50.24% (BGC-823) and 48.10% (MKN-45). CONCLUSION: All-trans retinoic acid may effectively inhibit the growth of xenograft tumor in spleen and its metastasis to liver in nude mice, which can be corroborated by the decrease of carcinoembryonic antigen and microvessel density.

Animals↗

PubMed2000

Vitamin D receptor gene polymorphism in postmenopausal women of the Han and Uygur nationalities in China.

OBJECTIVE: Polymorphism in vitamin D receptor (VDR) gene has been reported to play a major role in variations for genetic regulation of bone mass. Its role within various ethnic populations is not clear. The purpose of this study was to determine the frequencies of VDR genotypes in the Han and Uygur nationalities in China. METHODS: We analyzed the polymorphism of Bsm I restriction enzyme by PCR-RFLP technique in 162 healthy postmenopausal women of the Han nationality and 50 healthy postmenopausal women of the Uygur nationality in China. The genotype frequencies of VDR were calculated using Hardy-Weinberg equilibrium formula. RESULTS: In the Han nationality, the bb, Bb, and BB genotype accounted for 91.36%, 8.64% and 0%, respectively. In the Uygur nationality, frequencies were 74.00%, 18.00% and 8.00%, respectively. CONCLUSION: There was a significant difference between the Han and Uygur nationalities in the frequency distribution of VDR genotype (P < 0.01). Compared with the Caucasian population in the United States, Australia and France, there was a similar value to Uygur nationality in the BB genotype. This investigation gave us further evidence on the different etiopathology of osteoporosis in various ethnic groups.

Alleles↗

PubMed2000

Deletion of chromosomes 9p and 17 associated with abnormal expression of p53, p16/MTS1 and p15/MTS2 gene protein in hepatocellular carcinomas.

OBJECTIVE: Fifteen loci on chromosome 9p and 17 were analyzed to clarify the involvement of loss of heterozygosity (LOH) in hepatocellular carcinoma (HCC) in Chinese patients positive for hepatitis B (HBV) and/or hepatitis C (HCV) infection. Expression of tumor suppressor genes (TSG) of p53, p16, and p15 gene was found to correlate with a deletion of these genes. METHODS: Immunohistochemistry and PCR-based microsatellite polymorphism analysis techniques were used. RESULTS: A high frequency of LOH was detected on chromosome 9p24 at locus D9S54 (61.8%) and 9p21, concentrated at loci D9S1747 (52.4%) and D9S1752 (51.8%). On chromosome 17, high frequent LOH was concentrated on 17p at the p53 gene locus (53.8%) and locus D17S520 (52.8%). p53 protein expression was increased in HCC, which correlated with p53 gene loss. Expression of p16 and p15 protein decreased in HCC when LOH occurred at locus D9S1752 (p15 gene locus) or at locus D9S1747 and D9S1748 (p16 gene is located between these 2 loci). LOH at the p53 gene and p15 gene loci was closely associated with HBV and HCV co-infection in HCC. No significant relationship between LOH and HCC clinico-pathological outcomes was observed. CONCLUSION: High frequency LOH occurs on chromosomes 9p and 17 in HCC in Chinese patients. Such sites may contain several putative tumor suppressor genes critically involved in the development and/or progression of HCC. Deletion of p53, p16, or p15 tumor suppressor genes may cause abnormal expression of the protein product of these genes. HBV and/or HCV infection may be closely associated with LOH p53 and/or p15 gene expression.

Adult↗

PubMed2000

Radionuclide techniques for evaluating dilated cardiomyopathy and ischemic cardiomyopathy.

OBJECTIVE: To assess the clinical significance of radionuclide techniques in evaluating dilated cardiomyopathy (DCM) and ischemic cardiomyopathy (CAD-CM). METHODS: 28 patients with DCM and 55 patients with CAD-CM were studied. All patients underwent 99mTc-MIBI myocardial perfusion SPECT and 18F-FDG myocardial metabolic PET. 78 patients had 99mTc-RBC radionuclide ventriculography and 68 patients had coronary angiography. RESULTS: The results of 23 patients (82%) with DCM showed mild and non-segmental distribution perfusion abnormalities. 52 patients with CAD-CM (95%) showed perfusion abnormalities that distributed along the coronary vessel territories. Significant perfusion defects were found in 4 patients with DCM (14%) and 45 patients with CAD-CM (82%) (P < 0.01). The average perfusion score was 4.5 +/- 2.6 in DCM and 9.6 +/- 2.5 in CAD-CM and the area of diminished perfusion was significantly smaller in DCM than in CAD-CM (P < 0.001). Two patients with DCM and 18 patients with CAD-CM had metabolic defects. The patterns of perfusion/metabolic imaging showed mismatch in most patients with CAD-CM but match in most patients with DCM. The LVEF in patients with DCM and CAD-CM was both decreased but the decreases were not statistically different between DCM and CAD-CM. The RVEF in patients with DCM was significantly lower than that in patients with CAD-CM (32.4% +/- 13.9% vs 40.9% +/- 15.4%, P < 0.05). CONCLUSION: The radionuclide techniques are helpful for distinguishing DCM from CAD-CM. The segmental perfusion abnormality and RVEF are the most important factors for differentiation of DCM from CAD-CM.

Adult↗

PubMed2000

Mechanism of inhibition on activator protein-1 activity by all-trans retinoic acid in gastric cancer cells.

OBJECTIVE: To determine the mechanism of all-trans retinoic acid (ATRA) on growth inhibition in human gastric cancer cells. METHODS: Gastric cancer cell lines: MGC80-3, BGC-823, SGC-7901 and MKN-45. CAT assay, Northern blot, Western blot, gene transfection and MTT assay. RESULTS: ATRA can inhibit the activator protein-1 (AP-1) activity in ATRA-sensitive cell lines, but not in ATRA-resistant cell line, and the anti-AP-1 activity of ATRA is mediated by its receptor, retinoic acid receptor alpha (RAR alpha). ATRA can also inhibit the expression of cJun and cFos. One of the mechanisms for ATRA to inhibit the growth of gastric cancer cells may be through its inhibitory effect on the AP-1 activity and its influence on up-regulation of RAR alpha expression. The inhibition of cJun and cFos expressions by ATRA may also contribute to the anti-AP-1 activity. CONCLUSIONS: ATRA inhibits the growth of gastric cancer cells through the regulation of AP-1 activity. This action is mediated by RAR alpha.

Antineoplastic Agents↗

PubMed2000

[Mechanism of retinoic acid receptor alpha-mediated growth inhibition of gastric cancer cells by all-trans retinoic acid].

OBJECTIVE: To study the mechanism of retinoic acid receptor alpha(RAR alpha) in mediating growth inhibition of gastric cancer cells by all-trans retinoic acid(ATRA). METHODS: Expression of RAR alpha was detected by Northern blot. After anti-sense RAR alpha or sense RAR alpha had been transfected into gastric cancer cell lines BGC-823 and MKN-45 respectively, the inhibitory effect of ATRA on cell growth in stable clones was analyzed using MTT assay and colony forming assay in soft agar. The transcriptional activation of retinoic acid response element (RARE) was measured by CAT assay. RESULTS: ATRA could induce expression of RAR alpha in BGC-823 cells, but not in MKN-45 cells. In stable clones, ATRA could inhibit growth of MKN-45 cells transfected with RAR alpha gene, but could not inhibit that of BGC-823 cells transfected with antisense RAR alpha. Transient transfection and CAT assay showed higher beta-RAR response element (beta RARE) transcriptional activation induced by ATRA in MKN-45 cells transfected with RAR alpha compared to parental MKN-45 cells, while lower beta RARE transcriptional activation was seen in BGC cells transfected with antisense RAR alpha gene compared to parental BGC-823 cells. CONCLUSION: Sufficient level of RAR alpha is required for growth inhibition of gastric cancer cells by ATRA.

Antineoplastic Agents↗

PubMed2000

[Clinical pathological analysis of clear cell odontogenic carcinoma].

OBJECTIVE: To investigate clinical pathological characteristics and biologic behavior of clear cell odontogenic carcinoma. METHODS: Analysis of clinical data, microscopic and electromicroscopic observation of 8 cases of clear cell odontogenic carcinoma. RESULTS: The tumor occurred mainly in female and involved right mandible. 37.5% had regional lymph node metastases at the time of operation. Recurrence rate was 33.3%. The tumor had no capsule and consisted of clear cell and basaloid cells which arranged in nests and strands. Tumor cells often grew close to the blood vessels and caused bone resorption. There were less cell organelle and swelling of mitochondria. CONCLUSION: This tumor belongs to middle grade malignant tumor and should be called clear cell odontogenic carcinoma.

Adenocarcinoma, Clear Cell↗

PubMed2000

[Detection and effect of telomerase activity in oral mucosal squamous cell carcinoma].

OBJECTIVE: To study telomerase activity in 20 oral squamous cell carcinoma(SCC), and 10 normal oral tissues and 9 oral SCC and 9 adjacent normal tissue. METHODS: A modified PCR-based telomeric repeat amplification protocal assay(TRAP) was used. RESULTS: The telomerase activity was significantly higher in SCC than that of normal mucosa, and than that of adjacent tissue as well. CONCLUSIONS: These findings indicated that telomerase activation might be a critical step in the formation and development of cancer.

Carcinoma, Squamous Cell↗

PubMed2000

[The surgical experiences and risk factors of combined valvular procedure and myocardial revascularization].

OBJECTIVE: To introduce the experience of combined valve procedure and CABG. METHODS: 61 men and 15 women, with a mean age of 56 years, underwent combined valve procedure and CABG. CABG was performed with AVR (1 - 3 grafts) in 25 patients, with MVR (1 - 4 grafts) in 31 (MVR + AVP in 2, MVR + TVP in 3), with aortic and mitral valve replacement (1 - 3 grafts) in 18 (BVR + TVP in 2), with MVP (1 graft) in 1 and with MVP + TVP (1 graft) in 1 patient. Rheumatic disease was present in 67 and degenerative aortic and mitral valve disease was present in 9. SPSS statistical software was used to analyse the risk factors of the operation. RESULTS: 6 operative deaths (7.89%) occurred. 63 patients (63/70) who survived the operation were followed up for a mean period of 26.8 months. The function of heart in 62 patients was significantly improved. One patient died of SBE 9 months after operation. CONCLUSION: The combination of valve replacement or repair with coronary revascularization generally increases operative mortality. The hospital mortality is related to preoperative myocardial infarction, NYHA class IV, lower EF and the longer time of CPB and clamping aorta. Grafting in all significant coronary lesions, restoration of valvular function and good myocardial protection are the key factors for the success of CABG with valvular procedure.

Adult↗

PubMed2000

[Surgical treatment of anomalous origin of the left coronary artery from the pulmonary artery].

OBJECTIVE: To introduce the experience in surgical correction of anomalous origin of the left coronary artery from the pulmonary artery in 8 patients. METHODS: From 1991 August to 1999 March, 8 patients underwent surgery. Intrapulmonary tunnel procedure was performed in 7 patients, and coronary artery bypass grafting using the saphenous vein in 1. Mitral valve incompetence was repaired in 1 patient. ECG, echocardiographic and angiographic studies were made in all patients. 7 patients were followed up for 327 months (mean 46.8 +/- 10.7) months. RESULTS: No hospital deaths and later deaths occurred nor major complications during hospitalization. Because of suture of intrapulmonary tunnel loose, artery-pulmonary artery leakage 1 patient was reoperated on successfully. Follow-up showed cardiac function New York Heart Association function class I, mean LVMD (46.4 +/- 3.7) mm, vs mean (54.4 +/- 2.8) mm before the operation (P < 0.01), and mean EF (69.4 +/- 2.3)% vs mean 59.6% +/- 2.8% before the operation (P < 0.05). CONCLUSIONS: Anomalous origin of the left coronary artery from the pulmonary artery is a very rare congenital malformation. To correct the anomalous origin of the left coronary artery from the pulmonary artery is to reconstruct the normal two-coronary system and to treat the other associated diseases. Intrapulmonary tunnel operation is easy to perform satisfactorily.

Adolescent↗

PubMed2000

[Application of extracardiac conduit total cavopulmonary anastomosis].

OBJECTIVE: To evaluate the value of application of extracardiac conduit total cavopulmonary anastomosis (TCPA) in complex heart disease. METHODS: From June 1998 to August 1999, 10 patients with functional univentricular complex congenital heart diseases received TCPA. Eight patients were male and 2 female with a mean age of (9.0 +/- 5.6) years (from 2.5 to 21 years) and a mean weight of (25 +/- 14) kg (from 11 to 45 kg). Associated heart anomalies were TGA, PS or ASD. All surgical procedures were performed under general anesthesia and hypothermia. RESULTS: No operative and postoperative deaths and all patients were followed up for 6 - 18 months. All patients were clinically asymptomatic. There was no increase of systemic venous pressure. EKG revealed no arrhythmias. The cardiac function was in NYHA class I-II. CONCLUSIONS: Extracardiac conduit TCPA is a simple procedure and it is superior to others.

Adolescent↗